Overhead projectors for large audience presentations are well known in the prior art. Such systems typically utilize transparencies for conveying the information to be viewed by the audience.
With advances in modern liquid crystal technology, such transparencies have been replaced by full color liquid crystal display panels driven by video signal producing equipment, such as personal computers. In this regard, the liquid crystal display panel is typically positioned on the stage of an overhead projector to project an image onto a remote viewing surface.
While the above described projection system has proven to be highly successful, it would be desirable, for some applications, to eliminate the need for the separate overhead projector. Such a projector is not readily transportable by a business or other person who desires to travel from place to place for making sales or other types of presentations or the like.
Therefore, it would be highly desirable to have a new and improved compact projector, which is small in size and readily transportable, and yet is able to project video images, such as computer generated images.
In order to have such a transportable projection system, an integrated compact projection system has been employed and has been proven to be highly successful. The integrated system includes a computer driven display panel built into a small, low profile projector. Such an integrated projector is disclosed in the foregoing mentioned patent and patent applications.
Such an integrated compact projector is so small and compact that it can be readily carried, for example, onto an airplane. In this manner, an entire display presentation can be pre-programmed and stored in a small personal computer, and the projector can be readily transported therewith. Thus, a person can conveniently travel with the presentation equipment, for use when traveling.
While such a projector has proven to be overwhelmingly successful, it would be desirable to have a projector housing, which is even smaller in size, for a given size light source contained therewithin. The light source illuminating the image forming area produces diverging light, which requires by necessity a sufficiently large housing. If the light were somehow confined in a more limited space, the housing could, therefore, be decreased in size accordingly.
One attempt at addressing this problem included a technique used in a projection system for confining the light illuminating a display panel. For example, a display projection system is disclosed in U.S. Pat. No. 5,272,473 and 5,287,096, which are both incorporated herein by reference. Both patents teach the utilization of two angularly disposed serrated devices, referred to in the patent as "lenses," to confine light emitted from an image forming device, and to direct the light to a remotely located viewing surface. The configuration of serrated devices does apparently accomplish the desired effect of confining the light to the precise dimensions of a viewing surface, but there are several significant problems related to the use of such a technique. Firstly, the light image can become distorted as a result of the serrated devices producing a plurality of smaller light beams. While the serrated devices tend to expand the light image in both the horizontal and vertical dimensions, the stepped surfaces produce the smaller beams are spaced apart, thereby distorting the image. Moreover, since there are two serrated devices, the distortion is compounded.
As a consequence of such inherent distortion, the patented system employs a highly dispersive viewing surface, such as one having ground glass to blur the smaller beams together.
Therefore, it would be highly desirable to have a compact projection technique, which precisely controls the projection light without substantial image distortion.